Work proposed in this fellowship is aimed at gaining a greater understanding of the genetic mechanisms that regulate the control of glial development in vertebrates. Toward this aim, the role that the glial cells missing (gcm) gene plays in this process will be investigated. Two gain of function approaches are proposed to address this question. In the first specific aim, a standard transgenic approach will be utilized to drive ectopic expression of this gene to the mouse embryonic nervous system. In the second and third specific aims, a retroviral approach is proposed better understand the mechanism of how this gene may be involved in gliogenesis in the mammalian CNS. Specific aims two and three will be accomplished by the use of the novel technology of ultrasound guided microinjection to deliver engineered retrovirus to the early embryonic nervous system of the mouse. Results from this work can potentially lead to further insight into how cancers of glial origin arise, and novel gene therapy approaches designed to correct detrimental genetic mutations.